Uninstalling and Reinstalling Rage 128 Pro Ultra GL AGP drivers

I'm working on a 4400 Dell Dimension that has both power on trouble and then a windows XP Home video driver error when it does start. It all began shortly after the virus program caught and assumingly fixed a virus. The computer runs well when it starts, it always restarts properly, and even does cold boots fine without generating the driver error if the computer is somewhat warm, but when the computer has sat all night, the switch has to be turned on and off several times and then when it finally starts Windows begins and then generates an error saying that it needs a new video driver. It directs to the ATI website for the Rage 128 Pro Ultra GL AGP driver.

We've tried the driver XP directed us to and ended up getting the same error. Earlier I tried rolling back the driver using the XP features and I tried a system restore while in Safe mode to a point before all the troubles-- all to no avail. Even though device manager detects no problems I've also tried uninstalling the Rage 128 Pro that is listed in the driver list and have tried installing the original driver found on the Dell drivers disk. Somewhere in the process the system unexpectedly started using a driver that was labelled something like "16 MB Rage Pro". There may be some underlying conflict apparently, due to the installation of a non-dell ATI driver on top of the other.

I'm guessing the power on trouble is a power supply problem and not related to the video trouble, so I will eventually work on that; but before doing so I would like to fix the video problem and be ensured that the two are not related. I'm assuming I need to somehow to get a full and clean uninstall of all ATI and Dell drivers and then reinstall the original Dell driver? Am I on track? How can I do that? Could there be a relationship between the two problems? Thanks for the help.